Flirtations and Retributions
by LadyAkuma20
Summary: ADULT!Frisk x Sans! Frisk has some serious feelings for Sans... but she hasn't been able to flirt her way into a response... But, she's still filled with determination! And she's going to get her answers... and hopefully, have a BAD TIME in the process, hopefully before Papyrus gets home. (PWP!, ADULT!Frisk x Sans, Fem!Frisk)


****DISCLAIMERS! 1) I do NOT own Undertale or it** **'s characters. I just use them to make works of fanfiction, much of which is wholly non-canon. 2) I ONLY ship or write the ADULT!Frisk and Sans pairing. Note that Frisk is 19. She/He is an adult. I do not support the Child!Frisk with ANYONE pairings. All my fics that will or do involve Frisk will involve only consenting adults, and do not include any kind of pedophilia. 3) My version of Frisk for any Sans pairing is Fem!Frisk. Not that I don't support the Male!Frisk and Sans/Papyrus/Asriel/Etc pairings, but I don't write it well.**

Thanks! Back to your regularly scheduled programming!**

So much had changed…

Years had passed since Frisk had first fallen into the Underworld Ruins. Happily, she had opted to stay in the Underworld, with Toriel and Asgore. She had always been a frequent visitor to Snowdin, though, usually in the company of one of two, or both, skeleton brothers.

It was like this, surrounded by her extended family, that Frisk had grown from a little kid, all of 10 years old, to a budding 19 year old woman who had matured nicely.

Unfortunately for her, that had meant dealing with a rise in hormones and infatuation that her adoptive parents simply could not help her with. After all, she wasn't a monster, like them, and they had no idea what happened with humans and their hormones when they hit puberty.

It had been an awkward few months for her, since she had grown to avoid the object of her infatuation for a while. Once she had gotten her lust under control, she had begun visiting again. With that, she had decided to figure out if he felt the same way about her, as she did about him. However, Frisk had never been very good with words. So, she had gone for a more non-verbal method.

And, tempting the waters had been fun lately, but he hadn't paid her any mind, which had made her more nervous and unsettled than anything. In fact, as of lately, he hadn't even wanted to couch potato with her, which was usually his favorite activity…

And she needed answers…

Filled with determination to figure out what was going on with her favorite Snowdin skeleton, she quickly threw her hair in her short ponytail on top of her head, and changed, letting her lounge wear fall to the floor as she pulled on her favorite shorts and a pale blue spaghetti strap shirt. She grabbed her purple coat with the royal coat of arms on the back, and with that, she ran downstairs from her room, left a note for her parents, and headed out the door, towards Snowdin.

In Snowdin

Sans shifted uncomfortably on the couch, watching Mettaton's latest TV show with mild interest. Sighing, he let his head tilt back, his skull resting on the lumpy cushion of the couch.

How had things changed so much?

He felt like a grungy old pervert. (Even though he was only 26, but that was besides the point here…) Here he was, she wasn't even here, and his mind kept wandering to her. To the shape of her that had matured over the last few years, giving her a plump ass and perky breasts. To the moment where he had walked in as she bent over to get something out of the oven, and her shorts had slid up and showed the lines of her pretty ass cheeks, every detail and curve flaunted. He hadn't even noticed it until that point, but as she had stood up and her shirt had slid down off her shoulders…

He had noticed that his little Frisk had become a woman.

He'd been avoiding her, mainly because her mere presence was causing his cock, which didn't usually manifest unless he specifically willed it to, to start to appear without his control. Basically, a real, _bone-afide bone-r_.

Too bad he couldn't put it to use. There'd been plenty a night where his dirty sock tornado had gained an extra, sticky sock tossed into it as he'd manually fucked himself into satisfaction thinking about her. But there was no way in hell she would be into someone like him… not even someone as punny as he was.

He groaned as his mind wandered back to that day in the kitchen. That vision had given him so many orgasms over the last month and a half…

'Hell… Pap's not home… Not like anyone is going to walk in.' he thought, as he let his hand snake down and start rubbing on the glowing cock that had materialized. He bit back another groan, as he put gentle pressure over his shorts on the bulge that was hardening under his hand. His face flushed blue, as he put some pressure on the head, causing a damp spot to appear on his black shorts.

With that, he heard the door jiggle. If anything could kill a growing boner, it was the thought of someone walking in with it in your hand. Wide eyed, he willed it to de-materialize, as Frisk opened the door and put her coat on the coat rack. His jaw, which had already been set in a panicked look, had even more of one when he saw what she was wearing.

Sans damn near choked. It was those damn shorts again… and a pale blue, strapped shirt that showed off her perfect little tits.

He took a breath to steady himself, as she fixed her clothes and hair a bit, and praised everything that his shorts were black. As she sat next to him, he scooted over to give her more room. " 'Sup kiddo." he asked, flashing her his classic grin.

Frisk gave him a curious look, before shrugging. "Nothing much. Just coming over to be a pest, _tibi-honest_." she smirked, causing him to chuckle and relax. It was apparent that both of them had missed this interaction.

"Hope you like Mettaton's new show, then. It's different, to say the least." he said, focusing on the TV, as she nodded, sitting back and getting comfortable.

She appeared to watch the show, but in the back of her head, all she could think of was… well… how damn good he smelled, and how she wanted to lean into his arms and just kiss him. The though about doing what she'd dreamed of for months made her wet, and she shifted in her seat to try and absorb some of the dampness into her panties. He glanced down, throwing her a look. "You ok?"

She bit her lower lip, unknowingly causing mild shocks to go through him as he looked at her.

"Um. Yes and no." she muttered. He nodded.

"You ate at Grillby's. I told him not to make your 'burgs as greasy as he does the others. I think Paps might have some medicine that'll fix you right up, really get your gears _greased_ up and spinning right again." he said, as she blushed an adorable shade of pink and shook her head.

'No! It's not that. I haven't had anything from Grillby's since… I went with you." she said, quietly.

He blinked, then cleared his throat. She needed her best friend, and damn it, he'd put his lusting after her to the side to focus on her. "you know you can tell me anything." he grinned at her, as she nodded, and gulped.

"I… Am I ugly?"

Sans's face went blank at that, and then shocked. "How in the world can you think that?! Have you seen you?"

She shook her head. "Didn't seem to matter… Did…did you know I've been trying to hint that I was… maybe… into you… for weeks now?"

If skeletons could go pale, he would have. As it was, he blushed a bright blue. It'd… been on purpose? "you mean to tell me you were walking around, bendin' over and all that… on purpose?"

She nodded, sighing. "It was a stupid idea, but I was too…nervous… to talk to you. So I wanted to see your reaction… but you didn't have one… if anything, you pushed me away. Sans, I didn't want that! I'm sorry if I made you uncomfortable… I'll wear a raincoat forever, and long sweaters if that helps, if you stop avoiding me." she said, as he stared at her.

Had he been that oblivious?

She was into him? Holy shit, she was into him?

With that, as she grew quieter and her face grew sad, he grabbed her wrist, and pulled her against him, her lips hitting his mouth as he sent a jolt of his magic through her lips.

Frisk was stunned, but returned the kiss, before looking at him with shocked eyes. "But, I thought.."

He shrugged. "I've been avoidin' you because you have this way of making certain things… rise. Didn't think you'd be into me like that… so I just kinda… dropped the subject, by dealin' with it myself."

She blushed at the implications of that, but smiled.

However, she wasn't about to lose the moment. "How long will Papyrus be out?"

He looked thoughtful. "Eh… maybe another two hours. Why?"

He didn't have to ask, because Frisk took that moment to pull her shirt off, as his eyes widened. This was like every wet dream he'd had in the last few weeks, every single fantasy masturbation session, all coming true. He managed to choke out a response to the action, "Are you sure?"

She nodded, as his hands went to her bare waist. "I've been wanting to do this for two years or more… and we've been too stupid to just talk to each other…We have a lot of time to catch up on."

At that, he grinned, and gave his version of a wink. "Well, baby, if you're feeling _frisk-y_ … I can certainly be the _frenulum_ you need." As she groaned, but smirked, he let his hand slide up her leg to her grasp at her ass, squeezing the flesh under his grip with an almost predatory look in his eye, making Frisk shiver as she stood up. In a blink of blue, he was gone, and she looked around, confusion on her face.

"Sans? Where'd you go? Sa-EEP!" She was cut off by being pushed up and pinned against the wall, shaking the pictures hanging on it loose, a couple dropping to the floor. They were caught in blue magic and set down gently, and his glowing blue eye turned to focus on her, both of his hands pinning hers. He used his magic to pin her for a moment, throwing his over-sized blue coat to the ground as he brought his hands back up to pin her again.

"Just so you know, babe… you've been a fuckin' tease for weeks now. You've been squattin' and bendin' over in those tight ass shorts, givin' me a hard-on that wouldn't go away no matter how much I jerked off. I've had to deal with so many boners because of you, that I thought I was gonna need to spend the whole day away, gettin' off in my room. I got plans for a lot of payback… **You, girl, are in for a very bad time.** "

As she let another shiver go through her spine at the visual of Sans with his eye glowing, which she had found particularly hot as of lately, she squeaked as he used his magic to hold her in place, and younk her shorts off. He damn near lost his composure at the sight underneath her shorts, though. Just like the top, she was bare underneath, and he shuddered, his cock having long since materialized and was now growing hard underneath his shorts. He wasted no time in bringing two fingers down to her slit to play with her swollen bud, eliciting a groan from her. She bucked forward into his fingers, making them slide partially into her opening, as he let a grin grow on his face.

"Frisk…"

She stopped, panting, and looked at him. His grin spread, and he leaned forward, his mouth coming to a stop at her ear.

"I never would have _fingered_ you to be such a naughty girl."

Her eyes widened, and after a moment, she snorted, biting back laughter, tears forming at the corners of her eyes, as he grinned proudly, a smug look on his face.

"Sans… Oh my God… Papyrus would have smacked you for that one, just so you know." she said, biting back more laughter, as he shrugged, pulling her up against him, his cock pressing into her belly as he pushed them as close as they could go without actually penetrating her.

"Eh, I know. You could say…"

"Sans."

"I'd be _pun-ished_ for it. Eh?"

Her head dropped to his shoulder, as his look went from seductive to cute, as he snorted too, grinning widely.

"Never change, Sans." Frisk said, as he lifted her up in his arms bridal style, and looked at her face curiously. "Never let anyone convince you to change… I love the way you are, just like you were when we met."

He nodded, giving her a mock head-bow of a salute, as he carried her up to his room. "You got it, Frisk. Anything for you."

As he nudged his door open, he used his foot to give it a shove closed once they were in, and moved to the bed, his hands trailing on her ribcage, stroking underneath of her breasts with a smile on his face. She shivered, as his mouth went to nibble at her neck and collarbone area.

'Holy shit. This is happening. This is actually happening! I'm about to actually sleep with Sans...'

Frisk's head was spinning, and she let her hands trail up to his ribs under his shirt, as he stopped moving and shuddered, losing his composure, his cock twitching with need. She stopped, giving him a look. "Sans?"

He smiled weakly, taking deep, unsteady breaths. " 's OK. Just sensitive, that's all. Gotta remember, babe… we skeletons have our nerves in our bodies a bit different from you. Your skin is sensitive to touch… our bones are."

With that, she gave him a look, then allowed her fingers to trace his spine, making his arms shake as he held himself up, his eye flaring a bright blue. As her fingers found his pelvic bones, she used her nails on them gently, making him shout out, his eye letting out a deep glow as it seemed to roll back into his head.

With that, the seductive look was back, and he used his magic to pin her wrists above her, chuckling at the look that got him.

"Like I said, I planned for you to have a bad time, Frisk."

With that, he dipped his head between her thighs, using his magic to mimic a human tongue, a trick he'd learned years ago.

Her head was swimming, her hands balled into fists as they were pinned back by his magic, his tongue making magic between her legs, causing her mouth to drop as she gasped for a breath. Every time it touched her, it sent a jolt of his magic through her, causing everything down there to be more sensitive. Her breathing became more and more ragged, and his hand trailed up to her stomach, caressing her stomach, causing it to twitch under his touch as he continued his work.

Right as she felt herself beginning to tense up, beginning to moan his name, he stopped. She opened her eyes to look at him, as he gave her a devious look, licking her juices from his mouth, moving above her with a grin.

"What… what about you?" She managed to get out, looking down at his aching member, as he smirked at her in the way that only he could.

"Eh, that's what next time is for. I've been aching to bury myself between your legs for weeks now, though."

With that, her opening already slick, he pushed forward, groaning as he became enveloped in her heat, her head dropping back to the pillow as she sucked in a breath. Releasing his hold on her wrists, he began to move, letting his blue-magic tongue dangle out of his mouth, panting as he slammed into her, her hands snaking up to rest on his ribs, as he swallowed, breathing out and using a hand to lift her leg up, looking down at her and making eye contact.

"F-Frisk… 'm not gonna last long… Been wantin' this for weeks now…" he groaned, as she nodded, her hands caressing his ribs, making him grunt.

"I'm not gonna last long either… Sans, make me come…"

With that, his eye flared bright, and he began to slam into her harder and faster, making her arch off the bed. After all the foreplay and all the anticipation, she was already just about there, and his cock was hitting that spot she couldn't reach on her own just perfectly. Moments later, she felt her inner muscles clench and a wave of pleasure hit her, the tightness making Sans grunt and drop his head into her shoulder as he frantically thrust into her, spilling himself in her, and gripping her butt to pull her against him, plunging into her as deeply as he could.

As they began to relax, he smirked at her. "So… Now you really do have _spunk_."

Her eyes flew open to see a grinning Sans close enough where she could kiss him. "You…Jeez Sans!" she said as she collapsed into more giggles, making him chuckle.

"Instead of being _frisky_ … now, you're _spunky_."

More giggles ensued, and he pressed his mouth to her forehead, sending a warm jolt of magic through the kiss.

"Heh. I love hearing you laugh, Frisk."

They were interrupted in their moment by the sounds of the front door opening and closing, making both go wide eyed as they heard Papyrus's loud entrance.

"Shit. He's home early." Sans said, looking at Frisk.

"SANS! ARE YOU HERE?! YOUR COAT IS IN THE FLOOR… ALONG WITH SOME SHORTS! AND A SHIRT! WAS FRISK HERE? THESE LOOK LIKE HER THINGS!"

Frisk scrambled to wrap herself in Sans's sheets, as he made all of the mess and his dick de-materialize, and looked around for anything clean to let Frisk throw on, because Papyrus was loudly stomping up the stairs calling for Sans.

"SANS!"

Moments later, just as Sans tossed a semi-clean shirt to Frisk, the door flew open, causing Frisk to miss the shirt, it draping on her head, covering her head and arms.

"THERE YOU ARE! SANS, I WAS ABOUT TO MAKE SOME DINNER! DO YOU WANT SOME SPAGHETTI?"

Sans shook his head, grinning. "Nah, bro, I think there are more _pastabilities_ than spaghetti, don't you?"

"GRRRR…"

"I mean, I have a _penne_ for your thoughts on other things to make."

"SANS…"

"We do need to _rotini_ our meals, though, spaghetti every night is too much."

"DARN IT SANS! ENOUGH! I'M JUST GONNA GO DOWNSTAIRS! COME DOWN WHEN YOU'RE READY TO EAT!" Papyrus grumbled, as Sans grinned at him. He stopped at the door, and stared pointedly at the lump in his bed covered by a shirt. "AND CLEAN YOUR ROOM! WHAT WOULD FRISK SAY IF SHE SAW THIS? THAT LUMP IS EVEN SHAPED LIKE HER!" With that, he closed the door and walked out, throwing all the clothes he had picked up from the living room into the room.

Sans glanced at the shaking lump, and pulled his shirt off her, as she laughed quietly at him. "You almost got me busted, Sans!" she said, as he grinned.

"You probably already are. Why else would Papyrus throw all your clothes in here?"

She groaned in mortification, but grinned at him in return. She got up and threw her arms around him, causing him to hug her in return.

"Next time, just talk to me Frisk. I don't think I can take anymore hints from you." he said, as she grinned.

"Will do, Sans."

From downstairs, they heard a shout.

"SANS! TELL FRISK I SAID THAT I BOUGHT CHEESE! I REMEMBERED THAT SHE LIKES CHEESE!"

"Well. That answers that question."

Frisk just laughed, her head against his ribs as she chuckled. They were, indeed, busted.


End file.
